Analysis of chlorination by-products in swimming pool water by membrane introduction mass spectrometry - Influence of water physicochemical parameters

RATIONALE: Chlorine reacts in swimming pools with several compounds released by bathers to form disinfection by-products (DBPs). Epidemiological studies have shown adverse effects on health associated with the exposure to DBPs present in indoor swimming pool atmosphere. DBPs analyses require the use of multiple techniques depending on the targeted molecules. The measurement process itself is challenging due to the low stability of several compounds and the lack of specificity of certain methods. The Membrane Introduction Mass Spectrometry (MIMS) technique provides a solution to these problems by specific and sensitive in situ measurement of DBPs. This study investigates the effect of analytical conditions on quantification of DBPs and assesses the relevance of using MIMS for reliable analysis under typical swimming pool operating conditions. METHODS: MIMS is based on the simultaneous permeation of the selected compounds from the air or water samples through a polydimethylsiloxane (PDMS) membrane. DBPs are identified and quantified with a quadrupole analyzer after electron ionization. Limits of quantification (LOQs) of five DBPs are determined to assess the sensitivity of the system. Moreover, signal changes are monitored while varying physicochemical parameters such as temperature, pH and ionic strength. RESULTS: The mass spectra obtained for individual molecules show that the simultaneous measurement of trihalomethanes (THMs) and chloramines requires the monitoring of several ions and mathematical corrections of the signal. The pH and ionic strength of the solution do not significantly influence the determination of THMs. On the contrary, the temperature and hydraulics at the membrane interface must be controlled for accurate determination of DBPs. CONCLUSIONS: Results confirm that MIMS is a promising technology for the simultaneous quantification of volatile DBPs in both water and air of swimming pools. However, operating conditions such as membrane temperature should be treated with great care in order to avoid interferences.